A 66-year-old man presented with a rare case of a giant aneurysm of the internal carotid artery manifesting as difficulty in swallowing, resulting in severe malnutrition. Initial examination found a pulsating mass protruding from the posterior wall of the pharynx in the oral cavity. The patient had left hemiplegia caused by cerebral infarction one year previously. The patient underwent surgical therapy consisting of superficial temporal artery-middle cerebral artery bypass and trapping of the internal carotid artery. The pulsation of the oral mass vanished just after surgery and his difficulty in swallowing gradually improved. The patient was discharged with no new neurological deficits. The previous cerebral infarction was probably caused by an embolus from this giant aneurysm.